Starter freewheel and freewheel arrangement having a starter freewheel of this kind

ABSTRACT

A starter freewheel is provided. The starter freewheel has a first race, a second race, a wedging gap formed between the first and second races, at least one wedging element arranged in the wedging gap, and at least one further component. The further component is in rotary drive connection with one of the races. The component is formed by at least two sheet-metal parts connected to one another in sandwich-fashion. A freewheel arrangement having a starter freewheel of this kind is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of German Patent Application No.102013020327.9 filed Dec. 5, 2013, the disclosure of which is hereinincorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a starter freewheel having a firstrace, a second race, a wedging gap formed between the first and secondraces, at least one wedging element arranged in the wedging gap, and atleast one further component, which is in rotary drive connection withone of the races. The present invention furthermore relates to afreewheel arrangement for a drive train having a starter freewheel ofthis kind.

BACKGROUND OF THE INVENTION

Starter freewheels which have a first race, a second race, a wedging gapformed between the first and second races, at least one wedging elementarranged in the wedging gap, and at least one further component areknown in practice. The further components include a torque transmissionelement, which is used to transmit a torque to and/or from one of theraces, for example. In addition, there are known further components inthe form of side walls which delimit the abovementioned wedging gap inthe axial direction of the starter freewheel. For the purpose ofoptimizing the installation space in the axial direction, the componentsmentioned are often designed as sheet-metal parts or as formedsheet-metal parts in order to achieve a particularly lightweight starterfreewheel in addition.

The known starter freewheels have proven their worth but they aredisadvantageous to the extent that they tend to vibrate, the vibrationbeing due to the wedging elements or the spring elements of the wedgingelements or coming from outside, being introduced into the starterfreewheel by the starter or the output side of the driving unit, forexample. Thus, starting systems of this kind have a greater tendencytoward self-oscillations owing, for example, to the excitation due toany gearing that may be present between torque transmission elements.Such oscillations may not only affect the operation of the starterfreewheel but also, over and above this, sometimes lead to severe noisegeneration.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a starterfreewheel which, on the one hand, ensures reliable and continuousoperation and, on the other hand, leads to low noise generation. Anaspect of the present invention is furthermore based on an object ofproviding a freewheel arrangement for a drive train of a motor vehiclewhich has a starter freewheel with the above advantages.

This object is achieved by the features indicated in patent claims 1 and11, respectively. Advantageous embodiments of the invention form thesubject matter of the dependent claims.

The starter freewheel according to an embodiment has a first race, asecond race, a wedging gap formed between the first and second races andat least one wedging element within the wedging gap. The two races canbe arranged in a radially nested manner, for example, and therefore itis also possible to refer to an outer ring and an inner ring. The firstand/or second race is/are preferably designed as a sheet-metal part inthe form of an annular disk in order to ensure that the starterfreewheel has a small requirement for axial installation space. Inprinciple, the wedging element can have any desired outer contour,although it is preferred if the wedging element has a circular outercontour and is therefore designed as a wedging roller. Moreover, thestarter freewheel has at least one further component, which is in rotarydriving connection with one of the races, preferably being connected forconjoint rotation. The further component can be a torque transmissionelement for example, e.g. a starter wheel or a driving wheel, but it islikewise possible for the at least one further component to be formed bya side wall which serves to delimit the wedging gap and, if appropriate,to support the wedging element. The further component is formed by atleast two sheet-metal parts connected to one another sandwich-fashion.Since the at least one further component is formed by at least twosheet-metal parts connected to one another sandwich-fashion instead ofjust one sheet-metal part, both vibrations stemming from the freewheelitself, that is to say, for example, from the moving wedging element orfrom any spring elements present for preloading the wedging element, orthose introduced into the starter freewheel from outside, that is tosay, for example, by a starter or an output side of a driving unit, canbe damped in an effective manner, thus, on the one hand, ensuringreliable and continuous operation of the starter freewheel and, on theother hand, reducing noise generation in the region of the starterfreewheel.

In an embodiment of the starter freewheel, the two sheet-metal partswhich form the further component are connected to one anothernonpositively. Any nonpositive connection is possible here, although itis preferred if the nonpositive connection between the two sheet-metalparts is accomplished by screwing or riveting.

In another embodiment of the starter freewheel, the two sheet-metalparts forming the component are connected to one another positively.

In another embodiment of the starter freewheel, the two sheet-metalparts which form the abovementioned component are connected to oneanother materially. It is preferred here if the two sheet-metal partsare connected to one another by adhesive bonding or welding, althoughadhesive bonding is particularly preferred, especially since alarge-area connection between the two sheet-metal parts can thereby beachieved.

In another embodiment of the starter freewheel, the two sheet-metalparts which form the abovementioned component are connected to oneanother nonpositively, positively and/or materially, and it is thereforealso possible to speak of a combination of the various types ofconnection.

Although a significant reduction in vibrations and thus in noisegeneration can already be achieved through the sandwich-type connectionof the two sheet-metal parts without a layer in between, in anembodiment of the starter freewheel, the two sheet-metal parts areconnected to one another with a damping layer placed in between. It hasbeen found that a further reduction in vibration and thus greater noisereduction is thereby possible. Thus, in the case of sheet-metal partswhich are adhesively bonded to one another, the damping layer could beformed exclusively by the adhesive or an adhesive layer itself, but itis also advantageous if the damping layer is not formed by an adhesiveand, at most, is connected to the respective sheet-metal part by meansof an adhesive or in some other way, if appropriate materially,positively and/or nonpositively. In principle, it would also be possiblefor the damping layer to be formed by another sheet-metal part.

In another embodiment of the starter freewheel, the damping layer issofter and/or more flexible than the two sheet-metal parts in order toachieve improved damping and therefore a lower tendency to vibration andless noise generation. It is furthermore preferred here if the dampinglayer is formed from a viscoelastic and/or nonmetallic material.

In another embodiment of the starter freewheel, the damping layer isadhesively bonded to at least one of the sheet-metal parts in order tosimplify manufacture and to achieve large-area connection between thesheet-metal part or sheet-metal parts, on the one hand, and the dampinglayer, on the other. It has proven advantageous here if the dampinglayer is adhesively bonded to both sheet-metal parts which form theabovementioned component.

In another embodiment of the starter freewheel, the damping layer isvulcanized to at least one of the sheet-metal parts, preferably to bothsheet-metal parts. In other words, the damping layer was vulcanized toone or both sheet-metal parts, with said layer being bonded on.

In another embodiment of the starter freewheel, the damping layer isdesigned as a damping layer separate from the sheet-metal parts, whereinthe damping layer is clamped between the sheet-metal parts, which can beconnected to one another by screwing or riveting, for example, butalternatively also by welding.

In another embodiment of the starter freewheel, the at least onecomponent, which is formed by at least two sheet-metal parts connectedto one another sandwich-fashion, is a torque transmission element fortransmitting a torque to and/or from the race with which the componentis in rotary drive connection. Those vibrations, in particular, whichare introduced into the starter freewheel from the outside, e.g. fromthe output side of a starter or the output side of a driving unit, arethereby damped in an effective manner. Thus, it is ensured in thisembodiment that the vibrations introduced into the freewheel from theoutside do not have a disadvantageous effect on the operation of thestarter freewheel and/or lead to noise generation in the region of thestarter freewheel.

In another embodiment of the starter freewheel, the two sheet-metalparts which form the component in the form of a torque transmissionelement are connected to one another in such a way that the torque canbe transmitted via just one of the two sheet-metal parts. By virtue ofthis functional separation, tailored design of the two sheet-metal partsis possible. Thus, for example, a weight saving can be achieved sinceone sheet-metal part is made thinner than the other, torque-transmittingsheet-metal part of the torque transmission element.

In another embodiment of the starter freewheel, the torque transmissionelement is designed as a starter wheel for torque transmission betweenthe output side of a starter and one of the two races. In this case, thestarter wheel can furthermore have a starter ring which is connected forconjoint rotation to at least one of the two sheet-metal parts,preferably to the sheet-metal part transmitting the torque. As analternative, however, it is also possible for the starter ring to beformed integrally with at least one of the two sheet-metal parts,preferably with the sheet-metal part transmitting the torque.

In another embodiment of the starter freewheel, the torque transmissionelement is designed as a driving wheel which serves to transmit torquebetween the output side of a driving unit, that is to say, for example,the output shaft of an internal combustion engine, and one of the races.

In another embodiment of the starter freewheel, the at least onecomponent formed by the at least two sheet-metal parts connected to oneanother sandwich-fashion is a side wall for delimiting the wedging gapbetween the races. This embodiment is suitable particularly foreffectively damping the vibrations stemming from the starter freewheelitself, that is to say, for example, the vibrations caused by thewedging elements or the spring elements associated with the wedgingelements, and thus for ensuring reliable operation of the starterfreewheel and low noise generation in the region of the starterfreewheel. Here, the at least one side wall is preferably arranged insuch a way that the wedging element, a wedging element cage and/or aspring element for preloading the wedging element can be supported oris/are supported on the side wall.

In another embodiment of the starter freewheel, the sheet-metal part ofthe side wall which is adjacent to the wedging gap or at least the sideof said sheet-metal part which faces the wedging gap is more wearresistant and/or more corrosion resistant and/or less subject tofriction than the sheet-metal part of the side wall which is remote fromthe wedging gap or at least the surface of the sheet-metal part of theside wall which is remote from the wedging gap. It is thereby possibleto increase the life of the starter freewheel, while the hysteresisbehavior of the starter freewheel is also improved, this being the caseparticularly if the wedging element, a wedging element cage for thewedging element and/or a spring element for preloading the wedgingelement can be supported or is/are supported on the side wall, moreprecisely on the sheet-metal part of the side wall which is adjacent tothe wedging gap.

In principle, the side wall for delimiting the wedging gap does not haveto transmit any torque. Nevertheless, in another embodiment of thestarter freewheel, the side wall is likewise designed as a torquetransmission element. This can be accomplished, for example, by securinga torque transmission element on one of the two races with the side wallplaced in between, or by making the torque transmission element ofintegral design with the side wall, although the first-mentioned variantembodiment is preferred so as to achieve an advantageous functionalseparation here.

In another embodiment of the starter freewheel, the respective componentformed from the at least two sheet-metal parts connected to one anothersandwich-fashion is designed in such a way that the side face, facingthe one sheet-metal part, of the other sheet-metal part rests or issupported by at least 50%, preferably by at least 90%, particularlypreferably fully, on the one sheet-metal part, and, if appropriate, thiscan be accomplished with the abovementioned damping layer placed inbetween. In other words, the two sheet-metal parts forming the componentdo not necessarily have to be connected to one another completelysandwich-fashion, even though the greater the vibration or noisereduction is, the greater is the percentage mentioned.

In another embodiment of the starter freewheel, a spring element forpreloading the wedging element into a predetermined position isprovided—as already indicated above. Thus, the wedging element can bepreloaded by means of the spring element into a wedging position, inwhich the wedging element prevents a rotation of the first race relativeto the second race in a first circumferential direction, for example,wherein the wedging element can be moved counter to the restoring forceof the spring element into a release position, in which the first racecan be rotated relative to the second race in an opposite, secondcircumferential direction.

In another embodiment of the starter freewheel, the spring element hasan elongate spring body—similarly to a helical spring. However, theelongate spring body is not wound in a helix; on the contrary, theelongate spring body extends in a radial plane, i.e. in a plane definedby the radial directions of the starter freewheel, wherein the elongatespring body has a corrugated profile in the radial direction. It wouldalso be possible to say that the spring body has a corrugated profile inthe direction of the races situated opposite one another or arranged ina radially nested manner. Thus, for example, the elongate spring bodycan have an undulating or zigzag profile in the radial direction, whilethe elongate spring body extends in the radial plane. Since the elongatespring body extends in the radial plane, it is particularly suitable foruse within a wedging gap which has a particularly small extent or widthin relation to the axial direction. Thus, a freewheel with aparticularly small axial overall length can be created by virtue of thefact that the elongate spring body of the spring element extends in theradial plane. Moreover, the corrugated profile of the elongate springbody in the radial direction makes it possible for the spring element tohave a significantly greater extent in the radial direction than in theaxial direction. Consequently, a spring element of this kind is suitablefor extending over a large part of the width in the axial direction andsubstantially over the entire height of the wedging gap in the radialdirection and thus for largely filling the wedging gap. This has theadvantage that a wedging element designed to correspond to the wedginggap can be supported in a particularly reliable manner on the springelement without the need to take further measures in this regard, as isthe case, for example, with a spring element designed as a helicalspring which has the same extent in the axial direction and in theradial direction and is consequently not suitable for filling the heightof a relatively narrow wedging gap. The attachment, fastening or supportof the spring element on the first race, the second race or the sidewall is also thereby simplified.

In another embodiment of the starter freewheel, the spring body isformed by a sheet-metal part or wire. The sheet-metal part can beformed, for example, by a sheet-metal strip which has a corrugatedprofile in the radial direction, wherein the direction of the width ofthe sheet-metal strip in this case preferably corresponds to the axialdirection of the starter freewheel. The wire can have a circular crosssection, for example, thus making it possible to have recourse to astandardized or simple wire in the course of manufacturing the springelement, this reducing the outlay on manufacture.

In another embodiment of the starter freewheel, the corrugated profileof the spring body in the radial direction means that said body hasradially outer corrugation peaks and radially inner corrugation troughs,between which legs of the spring body can extend. Such legs arepreferably of rectilinear design or have a rectilinear profile. In thisembodiment, it is preferred if at least two, if appropriate at leastthree, corrugation peaks and at least two, if appropriate three,corrugation troughs are provided.

In another embodiment of the starter freewheel, the spring body hasdifferent widths in the axial direction of the starter freewheel. Inthis way, a potential contact area between a side wall and the springelement which may be supported on the side wall is reduced, with theresult that the friction between the spring element and the side wall isalso reduced. The result is that the hysteresis behavior of the starterfreewheel is improved. Moreover, unhindered operation of the springelement is ensured by virtue of the reduced friction between the springelement and the side wall.

In another embodiment of the starter freewheel, the spring body issecured on the first race, the second race and/or the side wall. Inorder to ensure simple assembly and secure retention of the spring bodyon the first race, the second race and/or the side wall in this case,the spring body is preferably secured with a latching action on thefirst race, the second race and/or the side wall.

In another embodiment of the starter freewheel, the wedging element isdesigned as a wedging roller. In this context, a wedging roller refers,in particular, to a wedging element having a circular circumference or acircular outer contour. Here, the ratio of a width to an outsidediameter of the wedging roller is preferably less than or equal to 1:2or 1:3, particularly preferably less than or equal to 1:4, ifappropriate less than or equal to 1:5. This has the advantage that it ispossible to provide a starter freewheel which has a small axial overalllength, especially since the wedging roller dimensioned in this wayitself has a relatively small axial extent, thus enabling the wedginggap too to have a correspondingly small extent in the axial direction ofthe starter freewheel. Moreover, the abovementioned spring element withthe elongate spring body which extends in a radial plane and has acorrugated profile in the radial direction unfolds, particularly forsupport, especially since only an appropriately designed spring body iscapable of reliably supporting the wedging element and of beingaccommodated effectively within the wedging gap dimensioned tocorrespond to the wedging element.

The freewheel arrangement is designed for a drive train, preferably adrive train within a motor vehicle, and has a starter freewheel of theabove-described type according to the invention.

In another embodiment of the freewheel arrangement, the starterfreewheel is designed as a dry-running freewheel, and therefore at leastthe wedging gap is not filled with a coolant and/or lubricant, such asoil or grease. On the contrary, it is preferred here if the starterfreewheel is arranged within a dry space or at least sealed off in anappropriate manner. Irrespective of this, however, the starter freewheelcan of course also be used in a wet space, and therefore it can inprinciple also be employed as a wet-running or wet starter freewheel.

In another embodiment of the freewheel arrangement, one of the races ofthe starter freewheel is in continuous rotary drive connection with theoutput side of a starter. It is preferred here if the continuous rotarydrive connection between the race and the output side of the starter isaccomplished via the abovementioned starter wheel.

In another embodiment of the freewheel arrangement, one of the races,preferably the race in continuous rotary drive connection with theoutput side of the starter, is supported on the output side of a drivingunit or on a fixed housing via a radial bearing, wherein the output sideof the driving unit can be the output shaft of an internal combustionengine, for example, and the fixed housing can be the housing of thedriving unit or of the internal combustion engine, for example. Arolling bearing can be taken into consideration as a radial bearing, forexample, and can furthermore be sealed off. However, it has provenadvantageous if the radial bearing is designed as a sliding bearing,wherein the sliding bearing should preferably be designed as a drysliding bearing or dry-running sliding bearing.

In another embodiment of the freewheel arrangement, the radial bearingis arranged between the race, on the one hand, and a supporting part,which is secured on the fixed housing and, if appropriate, is detachableand/or annular.

In another embodiment of the freewheel arrangement, a torquetransmission element is provided for transmitting a torque between anoutput side of a driving unit and one of the races. As already indicatedabove, the torque transmission element can form that component of thestarter freewheel which is formed by at least two sheet-metal partsconnected to one another sandwich-fashion. However, it is particularlypreferred here if the torque transmission element for transmitting thetorque between the output side of the driving unit and one of the racesis designed as a flexplate, thus allowing the torque transmissionelement to compensate both axial displacements of the output side of thedriving unit relative to the starter freewheel and also tilting of theoutput side of the driving unit relative to the axis of rotation of thestarter freewheel through appropriate deformation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 shows a partial side view of a freewheel arrangement having afirst embodiment of the starter freewheel according to the invention insection;

FIG. 2 shows a view along section line A-A in FIG. 1;

FIG. 3 shows a plan view of the spring body from FIG. 2 in isolation andon an enlarged scale;

FIG. 4 shows the starter freewheel from FIG. 2 with the wedging elementin the release position; and

FIG. 5 shows a partial side view of a freewheel arrangement having asecond embodiment of the starter freewheel according to the invention inpartial section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a first embodiment of the freewheel arrangement 2 accordingto the invention within a drive train of a motor vehicle. The freewheelarrangement 2 essentially has a starter freewheel 4, a starter 6, whichis indicated only schematically in FIG. 1, and a driving unit 8, theoutput side 10 of which is formed by an output shaft 12. The drivingunit 8 can be an internal combustion engine for example, and thereforethe output shaft 12 could also be referred to as a crankshaft.

In the figures, the mutually opposite axial directions 14, 16, themutually opposite radial directions 18, 20 and the mutually oppositecircumferential directions 22, 24 of the freewheel arrangement 2 and ofthe starter freewheel 4 are indicated by corresponding arrows, whereincircumferential direction 22 is also referred to below as the firstcircumferential direction 22 and circumferential direction 24 is alsoreferred to below as the second circumferential direction 24. The axisof rotation 26 of the output side 10 of the driving unit 8 and of thestarter freewheel 4 extends in the axial directions 14, 16. The firstand second circumferential directions 22, 24 can also be referred to asthe first and second directions of rotation.

The starter freewheel 4 has a first race 28 and a second race 30. In theembodiment illustrated, the first race 28 is designed as an outer ring,which is arranged to the outside of the second race 30 in radialdirection 18, and therefore it is also possible to refer in the case ofthe second race 30 to an inner ring. The two races 28, 30 are arrangedin a nested manner in the radial direction 18, 20, with the result thata wedging gap 32 running around in the circumferential direction 22, 24is formed between the first and second races 28, 30. At least onewedging element 34 of the starter freewheel 4 is arranged within thewedging gap 32. The starter freewheel 4 furthermore has furthercomponents, which are in rotary driving connection, in this caseconnected for conjoint rotation, with one of the races 28, 30. Thesefurther components are a starter wheel 36, a driving wheel 38, a firstside wall 40 and a second side wall 42, wherein said components will bedescribed in greater detail below.

The starter wheel 36 is designed as a torque transmission element and isused to transmit torque between an output side 44 of the starter 6,which here is designed as a pinion that can be driven by the starter 6,and the second race 30. The starter wheel 36 is composed essentially ofan outer ring gear 46, the teeth of which are in continuous rotarydriving engagement with the teeth of the pinion forming the output side44 of the starter 6, and of a sheet-metal section 48, which adjoins thering gear 46 on the inside in radial direction 20 and is connected forconjoint rotation to the second race 30 on the inside in radialdirection 20. The sheet-metal section 48 of the starter wheel 36 isformed by two sheet-metal parts connected to one anothersandwich-fashion, namely a first sheet-metal part 50 and a secondsheet-metal part 52. The side face 54 of the second sheet-metal part 52which faces the first sheet-metal part 50 and faces substantially inaxial direction 16 rests fully on the first sheet-metal part 50 or isfully supported on the first sheet-metal part 50. The sheet thickness ofthe second sheet-metal part 52 is made less than the sheet thickness ofthe first sheet-metal part 50. Of course, the sheet-metal parts 50, 52can also be arranged the opposite way round so that the side face of thesecond sheet-metal part 52 which faces the first sheet-metal part 50 andfaces substantially in axial direction 14 rests on and/or is fullysupported on the first sheet-metal part 50.

The second sheet-metal part 52 is connected to the first sheet-metalpart 50 in such a way that a torque is transmitted between the outputside 44 of the starter 6 and the second race 30 only via one of the twosheet-metal parts 50, 52, namely via the first sheet-metal part 50 butnot via the second sheet-metal part 52. In the embodiment illustrated,this is achieved by the fact that, on the one hand, the firstsheet-metal part 50 is connected for conjoint rotation to the secondrace 30, while the second sheet-metal part 52 is connected onlyindirectly, via the first sheet-metal part 50, to the second race 30and, on the other hand, the first sheet-metal part 50 is connected forconjoint rotation to the ring gear 46, while the second sheet-metal part52 is connected only indirectly, via the first sheet-metal part 50, tothe ring gear 46. At this point, it should furthermore be mentioned thatthe ring gear 46 of the starter wheel 36 can also be formed integrallywith the first sheet-metal part 50. Consequently, a torque transmissionpath 56 between the output side 44 of the starter 6 and the second race30, which is indicated in dashed lines in FIG. 1, passes via the ringgear 46 and the first sheet-metal part 50 but not via the secondsheet-metal part 52.

The driving wheel 38 serves to transmit torque between the output side10 of the driving unit 8 and the first race 28. In this arrangement, thedriving wheel 38 is secured for conjoint rotation on the inside inradial direction 20 on the output shaft 12 forming the output side 10 ofthe driving unit 8, while a section of the driving wheel 38 situated onthe outside in radial direction 18 is secured for conjoint rotation onthe first race 28, with the first side wall 40 described in greaterdetail below placed in between. The driving wheel 38 is formed by twosheet-metal parts connected to one another sandwich-fashion, namely afirst sheet-metal part 58 and a second sheet-metal part 60. The sideface 62 of the second sheet-metal part 60 which faces the firstsheet-metal part 58 and faces substantially in axial direction 14, restsfully on the first sheet-metal part 58 or is supported fully on thefirst sheet-metal part 58.

The two sheet-metal parts 58, 60 are connected to one another in such away that torque is transmitted between the output side 10 of the drivingunit 8 and the first race 28 only via one of the two sheet-metal parts58, 60, namely the first sheet-metal part 58. In other words, the torquetransmission path 64 between the output side 10 of the driving unit 8,on the one hand, and the first race 28, on the other hand, which isindicated in dashed lines in FIG. 1, runs via the first sheet-metal part58 but not via the second sheet-metal part 60, which is connected onlyindirectly, via the first sheet-metal part 58, to the output side 10 andthe first race 28.

In an alternative variant embodiment, which is likewise indicated inFIG. 1, the torque transmission element for transmitting a torquebetween the output side 10 of the driving unit 8 and the first race 28is designed as a “flexplate” which allows displacement of the outputside 10 in the axial directions 14, 16 and tilting of the output side 10relative to the axis of rotation 26 through appropriate deformation ofthe flexplate without the starter freewheel 4 itself having to perform acorresponding movement. Consequently, reliable and unaffected operationof the starter freewheel 4 is thereby ensured, even if the output side10 of the driving unit 8 performs said movements.

The first side wall 40 delimits the wedging gap 32 in axial direction14, wherein the first side wall 40 is connected for conjoint rotation bymeans of an outer section in radial direction 18 to the side of thefirst race 28 which faces in axial direction 14. In this case, the firstside wall 40 delimits the wedging gap 32 in such a way that at least thewedging element 34, a wedging element cage which may be present and/or aspring element, described in greater detail below, for preloading thewedging element 34 in axial direction 14 can be supported or is/aresupported on the first side wall 40. The first side wall 40 is formed bytwo sheet-metal parts connected to one another sandwich-fashion, namelya first sheet-metal part 66 and a second sheet-metal part 68, whereinthe first sheet-metal part 66 faces the wedging gap 32 and the firstrace 28 in axial direction 16. The side face 70 of the secondsheet-metal part 68 which faces the first sheet-metal part 66 and facessubstantially in axial direction 16 rests fully on the first sheet-metalpart 66 or is supported fully on the first sheet-metal part 66.

The first sheet-metal part 66 or at least the side 72 thereof whichfaces the wedging gap 32 is more wear resistant and/or corrosionresistant and/or less subject to friction than the second sheet-metalpart 68 remote from the wedging gap 32 or at least the surface or sideface 70 thereof. This can be achieved, for example, through appropriateselection of the material for the first sheet-metal part 66 and thesecond sheet-metal part 68, but it is likewise possible to treat thesurface of the side 72 of the first sheet-metal part 66 in anappropriate manner or even to provide it with a wear resistant,corrosion resistant and/or low friction coating. As previously in thecase of the second sheet-metal parts 52 and 60 of the starter wheel 36and of the driving wheel 38, respectively, the second sheet-metal part68 of the first side wall 40 also has a smaller sheet thickness than thefirst sheet-metal part 66 of the first side wall 40.

As already indicated above, the driving wheel 38 or the flexplate issecured for conjoint rotation on the first race 28, with the first sidewall 40 placed in between, with the result that the first side wall 40is likewise designed as a torque transmission element in the embodimentillustrated, especially since the torque transmission path 64 betweenthe output side 10 of the driving unit 8 and the first race 28 alsopasses via a section of the first side wall 40. However, this does notnecessarily have to be the case. On the contrary, the driving wheel 38or the flexplate can also be secured on the first race 28 whilebypassing the first side wall 40, with the result that the torquetransmission path 64 does not pass via the first side wall 40 either,which therefore does not act as a torque transmission element. Moreover,the second sheet-metal part 68 of the first side wall 40 could besecured in such a way on the first sheet-metal part 66 of the first sidewall 40 that the torque transmission path 64 passes only via the firstsheet-metal part 66 but not via the second sheet-metal part 68 of thefirst side wall 40. It would also be possible for the two sheet-metalparts 66, 68 to be connected to one another in such a way that thetorque transmission path 64 passes only via the second sheet-metal part68 and not via the first sheet-metal part 66 of the first side wall 40.In the two last-mentioned cases, the respective sheet-metal part 68 or66 would have to be arranged further inward in radial direction 20 onthe other sheet-metal part 66 or 68 in order to position it outside thetorque transmission path 64.

The second side wall 42 delimits the wedging gap 32 in axial direction16, wherein the second side wall 42 is secured for conjoint rotation forthis purpose on the side of the first race 28 which faces in axialdirection 16 and extends inward in radial direction 20 in order todelimit the wedging gap 32 in the manner stated. In the embodimentillustrated, the second side wall 42 does not form a torque transmissionelement via which a torque could be transmitted to the first race 28from another component or to another component from the first race 28.At least the wedging element 34, any wedging element cage that ispresent and/or a spring element, described in greater detail below, forpreloading the wedging element 34 in axial direction 16 can be supportedor is/are supported on the second side wall 42. The second side wall 42is also formed by two sheet-metal parts connected to one anothersandwich-fashion, namely a first sheet-metal part 74 and a secondsheet-metal part 76, wherein the first sheet-metal part 74 is adjacentto the wedging gap 32 in axial direction 14. The side face 78 of thesecond sheet-metal part 76 which faces the first sheet-metal part 74rests fully on the first sheet-metal part 74 or is supported fully onthe first sheet-metal part 74.

The first sheet-metal part 74 adjacent to the wedging gap 32 or at leastthe side 80 thereof which faces the wedging gap 32 is more wearresistant and/or corrosion resistant and/or less subject to frictionthan the second sheet-metal part 76 remote from the wedging gap 32 or atleast the surface or side face 78 thereof, it being possible to achievethis by appropriate selection of materials, surface treatment orcoating, for example, as already described with reference to the firstside wall 40. In the case of the second side wall 42 too, the secondsheet-metal part 76 has a smaller sheet thickness than the firstsheet-metal part 74. As already in the case of the first side wall 40,it would also be possible here in principle for both sheet-metal parts74, 76 of the second side wall 42 to be provided with an appropriatecoating but, in the case of the first-mentioned variant, it is possibleto dispense with the coating of the second sheet-metal part 76, reducingthe outlay on manufacture.

In the above description, it is stated that the side faces 54, 62, 70and 78 of the second sheet-metal parts 52, 60, 68 and 76 which face thefirst sheet-metal parts 50, 58, 66 and 74, respectively, each rest orare supported fully on the other sheet-metal part 50, 58, 66 or 74,respectively. As an alternative, however, it may also already besufficient to achieve the advantages stated at the outset if the sideface 54, 62, 70 or 78 of the second sheet-metal part 52, 60, 68 or 76which faces the first sheet-metal part 50, 58, 66 or 74, respectively,rests or is supported by at least 50%, preferably by at least 90%, onthe first sheet-metal part 50, 58, 66 or 74, respectively, although fullcontact or support is particularly preferred here.

The two sheet-metal parts 50, 52 of the starter wheel 36, the twosheet-metal parts 58, 60 of the driving wheel 38, the two sheet-metalparts 66, 68 of the first side wall 40 and the two sheet-metal parts 74,76 of the second side wall 42 can be connected to one anothernonpositively, positively and/or materially in order to connect saidsheet-metal parts to one another for conjoint rotation, said parts beingconnected to one another sandwich-fashion. In the case of a nonpositiveconnection, this is preferably brought about by screwing or riveting,although a corresponding illustration of screws or rivets has beenomitted in the figures. In the case of a material connection, thesheet-metal parts connected to one another sandwich-fashion arepreferably bonded to one another adhesively or welded to one another,adhesive bonding being particularly preferred, especially since it ispossible by this means to achieve a particularly large-area connectionbetween the sheet-metal parts connected to one another sandwich-fashion.

In the embodiment illustrated, the sheet-metal parts 50, 52, 58, 60, 66,68, 74, 76 are substantially in the form of annular disks. However, thisdoes not necessarily have to be the case. Thus, although it is preferredif at least the first sheet-metal parts 50, 58, 66, 74 are substantiallyin the form of annular disks, it is also possible to dispense with theintegral and/or annular-disk-shaped second sheet-metal part 52, 60, 68,76 in favor of a plurality of second sheet-metal parts in each case,these being spaced apart and connected to the respective firstsheet-metal part 50, 58, 66, 74 and, if appropriate, being arranged inseries in the circumferential direction 22, 24 on the first sheet-metalpart 50, 58, 66, 74.

The second race 30 is supported both in radial direction 18, 20 and inaxial direction 14, 16 on a fixed housing 84 by means of a radialbearing 82, which in this case is designed as a dry sliding bearing.Here, the fixed housing 84 is the housing of the driving unit 8. As analternative, it would also be possible for support to be provided on theoutput side 10 of the driving unit 8, in the present example thereforeon the output shaft 12, by means of the radial bearing 82. In theembodiment illustrated, mounting or support is not provided directly onthe fixed housing 84 by means of the radial bearing 82, however; on thecontrary, the radial bearing 82 is arranged between the second race 30,on the one hand, and an annular supporting part 86 secured detachably onthe fixed housing 84. The supporting part 86 has an outer encirclingrecess 88, into which the second race 30 can be inserted in axialdirection 16 in order to provide support or mounting in radial direction18, 20 and in axial direction 16. Once the second race 30 has beenintroduced into the encircling recess 88, an encircling supporting partcover 90 can be secured in such a way on the supporting part 86, ifappropriate detachably, that the encircling recess 88 is bounded inaxial direction 14 by the supporting part cover 90, thus also providingsupport or mounting of the second race 30 in axial direction 14 on thesupporting part 86 and thus on the fixed housing 84 by means of thesupporting part cover 90. This significantly simplifies the assembly ofthe starter freewheel 4. As indicated in FIG. 1, an antifriction part orantifriction coating 92 can be secured on the second race 30 in order toachieve the sliding bearing arrangement, said part or coating beingintroduced into the abovementioned encircling recess 88. In acorresponding manner, an antifriction part or antifriction coating canalso be provided in the encircling recess 88 itself.

As can furthermore be seen from FIG. 1, the supporting part 86 has notonly the encircling recess 88 provided on the outside in radialdirection 18 on the supporting part 86 but also an encircling recess 94on the side facing inward in radial direction 20, said recess 94 beingdelimited in axial direction 16 by the supporting part 86 and in axialdirection 14 by the supporting part cover 90 secured detachably on thesupporting part 86. On the output side 10 of the driving unit 8 or theoutput shaft 12, on the other hand, there is secured a limiting part 96,which is fixed in relation to the axial directions 14, 16 on the outputside 10 and extends outward into the encircling recess 94 in radialdirection 18. Thus, the limiting part 96 in conjunction with theencircling recess 94 serves to limit the ability of the output side 10to move in relation to the supporting part 86 and thus in relation tothe second race 30 of the starter freewheel 4. Consequently, thesupporting part 86 in conjunction with the supporting part cover 90 hasa dual function.

In the illustrated embodiment of the freewheel arrangement 2, thestarter freewheel 4 is designed as a dry-running freewheel, i.e. nocoolant and/or lubricant, e.g. oil or grease, is provided, at leastwithin the wedging gap 32. However, irrespective of the embodimentillustrated, it is understood that the starter freewheel 4 describedherein can likewise be of wet-running design in order to achieve theadvantages stated at the outset.

The wedging element 34 is designed as a wedging roller and has a width bin axial direction 14, 16 and an outside diameter a. The ratio of thewidth b to the outside diameter a of the wedging element 34 designed asa wedging roller is less than or equal to 1:2 or 1:3, preferably lessthan or equal to 1:4, particularly preferably less than or equal to 1:5.Thus, it is also possible to speak of a wedging element 34 in the formof a circular disk or coin.

As can be seen particularly from FIG. 2, each of the wedging elements 34is assigned a spring element 98 for preloading the wedging element 34into a predetermined position relative to the first race 28, which isdesigned as an outer ring. In the present example, the spring element 98is used to preload the wedging element 34 into the wedging positionshown in FIG. 2. The wedging elements 34 can each be moved from thewedging position according to FIG. 2, in which the wedging element 34prevents a rotation of the first race 28 relative to the second race 30in the first circumferential direction 22, counter to the restoringforce of the spring element 98 into a release position, which is shownin FIG. 4, in which the first race 28 can be rotated in the opposite,second circumferential direction 24 relative to the second race 30.Thus, in terms of its basic construction, the starter freewheel 4described here is a “one-way clutch”. In this case, the respectivewedging element 34 is preloaded into the tapering wedging gap 32 incircumferential direction 24 with the aid of the spring element 98.

The spring element 98 has an elongate spring body 100. As can be seenparticularly from FIG. 3, the elongate spring body 100 is designed as asheet-metal part, in this case as an elongate sheet-metal strip. As analternative to the sheet-metal part or sheet-metal strip, however, it isalso possible to use a wire as spring body 100. In contrast to a helicalspring, the spring body of which, generally a wire, is helically wound,the elongate spring body 100 of the spring element 98 extends in aradial plane defined by the radial directions 18, 20, wherein the springbody 100 has a corrugated profile in radial direction 18, 20. Here, thewidth direction of the sheet-metal strip used as a spring body 100 inthe present embodiment corresponds substantially to the axial directions14, 16.

Owing to its corrugated profile in radial direction 18, 20, the springbody 100 has radially outer corrugation peaks 102 and radially innercorrugation troughs 104, between which legs 106 of the elongate springbody 100 extend, preferably in a straight line. Consequently, the legs106 are arranged substantially in alignment with one another incircumferential direction 22, 24. The radially outer corrugation peaks102 can be supported or are supported in radially outward direction 18on the first race 28 or the inside thereof, while the radially innercorrugation troughs 104 are preferably spaced apart in radial direction18, 20 from the second race 30 or the outside thereof.

The spring body 100 furthermore has a supporting section 108 adjacent tothe wedging element 34, on which wedging element 34 can be supported oris supported, and a fastening section 110 remote from the wedgingelement 34. The fastening section 110 of substantially U-shaped designis used for the latch-action fastening of the spring body 100 or of thespring element 98 on the first race 28, which has a projection 112projecting into the wedging gap 32 in radial direction 20 for thispurpose. The fastening section 110 engages with a clamping or latchingaction behind the projection 112, both in the circumferential directions22, 24 and in the radial directions 18, 20, in order to bring aboutreliable fastening of the spring element 98 on the first race 28. As analternative, the fastening section 110 of the spring element 98 or ofthe spring body 100 thereof can also be fastened with a latching actionon the second race 30 or one of the two side walls 40, 42, wherein acorresponding projection 112 projecting into the wedging gap 32 couldthen be provided on the second race 30, the first side wall 40 or thesecond side wall 42.

As can be seen from FIG. 3, the spring body 100 has different widths inthe axial direction 14, 16 in relation to the direction of extentthereof. Thus, in the embodiment illustrated, the corrugation peaks 102,the corrugation troughs 104, the fastening section 110 and thesupporting section 108 have a greater width in the axial direction 14,16 than the legs 106. In this way, any contact area between the springelement 98 or the spring body 100 and the side walls 40, 42 is reduced,which results or would result in reduced friction.

A second embodiment of the freewheel arrangement 2 is described belowwith reference to FIG. 5, said embodiment corresponding substantially tothe first embodiment according to FIGS. 1 to 4, and therefore only thedifferences will be discussed below, identical reference signs will beused for identical or similar parts and the preceding description ofFIGS. 1 to 4 otherwise applies accordingly.

Whereas, in the case of the embodiment according to FIG. 1, the mutuallyassociated sheet-metal parts 50, 52 of the starter wheel 36, themutually associated sheet-metal parts 58, 60 of the driving wheel 38,the mutually associated sheet-metal parts 66, 68 of the first side wall40 and the mutually associated sheet-metal parts 74, 76 of the secondside wall 42 each rest on one another or are supported on one anotherdirectly or, at most, via the intermediary of an adhesive, the mutuallyassociated sheet-metal parts in the second embodiment according to FIG.5 rest on or are supported on one another with a damping layer 114placed in between. In other words, the two sheet-metal parts 50, 52 ofthe starter wheel 36, the two sheet-metal parts 58, 60 of the drivingwheel 38, the two sheet-metal parts 66, 68 of the first side wall 40 andthe two sheet-metal parts 74, 76 of the second side wall 42 areconnected to one another with a damping layer 114 placed in between. Thedamping layer 114 is softer and/or more flexible than the firstsheet-metal part 50, 58, 66 and 74, respectively, on the one hand, andthe second sheet-metal part 52, 60, 68 and 76, respectively, on theother hand.

In principle, the damping layer 114 could also be formed by asheet-metal part, but it has proven advantageous if the damping layer114 is formed from a viscoelastic and/or nonmetallic material. Moreover,the damping layer 114 is adhesively bonded to at least one of the firstor second sheet-metal parts 50, 58, 66, 74; 52, 60, 68, 76, it havingproven advantageous if the damping layer 114 is adhesively bonded bothto the first and to the second sheet-metal part of the respective pairof sheet-metal parts. As an alternative or supplementary measure, thedamping layer 114 can have been subjected to vulcanization, in whichcase the damping layer 114 is then vulcanized to at least one of thefirst and second sheet-metal parts 50, 58, 66, 74; 52, 60, 68, 76,preferably to both sheet-metal parts 50, 52; 58, 60; 66, 68; 74, 76 inorder to achieve adhesion of the damping layer 114 to one or bothsheet-metal parts of the respective pair of sheet-metal parts. Inprinciple, it is furthermore also possible for the damping layer 114 tobe formed as a damping layer 114 which is separate from the sheet-metalparts of the respective pair of sheet-metal parts and which is thenclamped between the mutually associated sheet-metal parts 50, 52; 58,60; 66, 68; 74, 76, which can be connected to one another nonpositively,preferably by screwing or riveting, positively or materially, preferablyby welding, for example. In the case of sheet-metal parts which areadhesively bonded to one another, the damping layer 114 could be formedexclusively by the adhesive or an adhesive layer itself, but it is alsoadvantageous if the damping layer 114 is not formed by an adhesive andis at most connected to the mutually associated sheet-metal parts 50,52; 58, 60; 66, 68; 74, 76 by means of an adhesive or in some other way,if appropriate materially, positively and/or nonpositively.

It is furthermore common to both embodiments according to FIGS. 1 and 5that a subsequent component 116, which is driven by means of the outputside 10 of the driving unit 8 and can be formed by a clutch, ahydrodynamic converter, a flywheel or similar, for example, is in rotarydriving connection with the output side 10 of the driving unit 8 bymeans of the driving wheel 38 designed as a flexplate in such a way thatthe driving wheel 38 designed as a flexplate also acts between theoutput side 10 and the subsequent component 116. This has the advantagethat displacement of the output side 10 in the axial direction 14, 16and/or tilting of the output side 10 relative to the axis of rotation 26is accepted by the driving wheel 38 designed as a flexplate and is thustransmitted at most in attenuated form to the subsequent component 116.

What is claimed is:
 1. A starter freewheel having a first race a secondrace a wedging gap formed between the first and second races, at leastone wedging element arranged in the wedging gap, and at least onefurther component, which is in rotary drive connection with one of theraces, wherein the further component is formed by at least twosheet-metal parts connected to one another sandwich-fashion.
 2. Thestarter freewheel as claimed in claim 1 wherein the two sheet-metalparts are connected to one another nonpositively, positively, or acombination of nonpositively and positively.
 3. The starter freewheel asclaimed in claim 1 wherein the two sheet-metal parts are connected toone another with a damping layer placed in between, wherein the dampinglayer is softer and/or more flexible than the two sheet-metal parts. 4.The starter freewheel as claimed in claim 3 wherein the damping layer isformed from a viscoelastic and/or nonmetallic material.
 5. The starterfreewheel as claimed in claim 3 wherein the damping layer is adhesivelybonded to at least one of the sheet-metal parts.
 6. The starterfreewheel as claimed in claim 3 wherein the damping layer is vulcanizedto at least one of the sheet-metal parts.
 7. The starter freewheel asclaimed in claim 3 wherein the damping layer is clamped between thesheet-metal parts as a damping layer separate from the sheet-metalparts.
 8. The starter freewheel as claimed in claim 1 wherein the atleast one further component is a torque transmission element fortransmitting a torque to and/or from the race with which the componentis in rotary drive connection, wherein the two sheet-metal parts areconnected to one another in such a way that the torque can betransmitted via just one of the two sheet-metal parts, and the torquetransmission element forms a starter wheel for torque transmissionbetween the output side of a starter and the race or a driving wheel fortorque transmission between the output side of a driving unit and therace.
 9. The starter freewheel as claimed in claim 1 wherein the atleast one further component is a side wall for delimiting the wedginggap, on which the wedging element, a wedging element cage and/or aspring element for preloading the wedging element is supported, whereinthe sheet-metal part adjacent to the wedging gap or at least the side ofsaid sheet-metal part which faces the wedging gap is more wear resistantand/or more corrosion resistant and/or less subject to friction than thesheet-metal part remote from at least a surface of the wedging gap andthe side wall comprises the torque transmission element.
 10. The starterfreewheel as claimed in claim 1 wherein the side face, facing the onesheet-metal part, of the other sheet-metal part rests or is supported byat least 50% on the one sheet metal part, with the damping layer placedin between.
 11. The starter freewheel as claimed in claim 1 wherein theside face, facing the one sheet-metal part, of the other sheet-metalpart rests is fully supported on the one sheet metal part, with thedamping layer placed in between.
 12. The starter freewheel as claim inclaim 10 wherein the damping layer is placed between the side face andthe one sheet metal part.
 13. The starter freewheel as claimed in claim1 further comprising a spring element for preloading the wedging elementinto a predetermined position, said spring element having an elongatespring body, which extends in a radial plane and has a corrugatedprofile in the radial direction and is formed by a sheet-metal part orwire.
 14. The starter freewheel as claimed in claim 13 wherein thespring body has different widths in the axial direction of the starterfreewheel and/or is secured on the first race, the second race and/orthe side wall.
 15. The starter freewheel as claimed in claim 1 whereinthe wedging element comprising a wedging roller, wherein the ratio of awidth (b) to an outside diameter of the wedging roller is less than orequal to 1:2.
 16. The starter freewheel as claimed in claim 1 whereinthe wedging element is designed as a wedging roller, wherein the ratioof a width (b) to an outside diameter of the wedging roller is less thanor equal to 1:3.
 17. The starter freewheel as claimed in claim 1 whereinthe wedging element is designed as a wedging roller, wherein the ratioof a width (b) to an outside diameter of the wedging roller is less thanor equal to 1:5.
 18. A freewheel arrangement for a drive train having astarter freewheel wherein the starter freewheel is a dry-runningfreewheel and/or one of the races is in rotary drive connection with theoutput side of a starter.
 19. The freewheel arrangement as claimed inclaim 18, wherein one of the races is supported on the output side of adriving unit or on a fixed housing via a radial bearing, wherein theradial bearing is arranged between the race and a supporting part, whichis secured on the fixed housing.
 20. The freewheel arrangement asclaimed in claim 19 wherein a torque transmission element is providedfor transmitting a torque between an output side of a driving unit andone of the races, said torque transmission element comprising aflexplate.